Arctic's sea-ice shrinkage outpacing modelling

On July 5th 2013, adventurer Kevin Vallely and a trio of fellow Vancouverites set out to row Canada's storied Northwest Passage to raise awareness around climate change. A noble way to marry adventure to issue, the very attempt accomplished part of the goal, since not so long ago, when thick ice choked this island labyrinth most of the summer, the planned 75-day, 3,000-kilometre journey from the western side of Canada's Arctic archipelago to its eastern gateway would not have been possible.

The expedition, however, was up against it from the start, fighting strong winds and ice conditions unseen for decades. Although 2013 ice cover was still a sobering 1.41 million km2 less than the 30-year average (for comparison, the combined area of B.C. and Alberta is 1.6 million km2), by August, prevailing winds choked most of the passage's eastern reaches with loose pack ice. After rowing an impressive 1,860 km in 55 days, the group pulled out for safety reasons at Cambridge Bay when ice and the September weather window closed in. They weren't alone, as unusual ice conditions caused others to surrender similar efforts: a tandem kayak and two other rowing expeditions, a group of Americans attempting the passage on jet skis for the reality TV show Dangerous Waters, sailboats of every description, a super yacht, hovercraft, research vessels and even cruise ships had, with good reason, all expected to make it through. At the time, of 185 successful Northwest Passage attempts since Roald Amundsen's 1903 navigational triumph, 109 of these had been accomplished since the millennium—a telling statistic regarding a warming Arctic, yet one now dismissed by critics.

"Climate-change deniers seized on our truncated journey as evidence of an Arctic unaffected by climate change," recalls Vallely. "Though nothing was further from the truth. Despite the tough conditions, maximum ice extent in 2013 was still the sixth-lowest ever recorded. Climate change is real and everything we saw and everyone we talked to reinforced that it is profoundly affecting the Arctic."

This is what we know: while average global temperature increased 0.85C from 1880 – 2012, the Arctic has warmed 3.0C in the past three decades alone; polar ice is melting, sea level is rising, and snow and ice cover that normally reflects sunlight back into the atmosphere is receding, creating a positive feedback loop of melting and warming and increasingly extreme weather. Related are precipitous declines in the thickness and extent of glaciers (this May, a U.S. study cited B.C.'s 17,000 glaciers as receding "at an alarming rate") and snow cover, which now disappears from Canada's north an average three weeks earlier than in 1950. The most sensitive barometer of change, however, remains the extent of Arctic sea ice, which has declined 12 per cent each decade since the 1970s.

Sea-ice shrinkage in the northern hemisphere has, in fact, outpaced all models: levels predicted for 2025 were actually achieved in 2007, and 2012 beat that record by half. The total volume of Arctic ice has diminished by almost 50 per cent since 2004 — and not simply due to warm summers. Milder winters ensure that ice which does form is less substantive: the average thickness of sea ice globally has decreased 30 – 50 per cent. Because thinner ice is flatter, melt ponds accumulate on the surface, reducing reflectivity, absorbing more heat, and allowing more sunlight into the ocean, which in turn weakens the ice and warms the ocean even more — another feedback loop. Though summer 2013 proved cold by recent standards, spring breakup began 57 days earlier than average. May 2014 saw the third lowest extent of Arctic sea ice recorded for that month while scientists reported the sudden breakup of the 2.2 million km3 western Antarctic ice sheet as now irreversible.

With northern reaches of the globe warming at twice the rate as the equator, hotter conditions are causing more widespread forest fires. The combined boreal forests of Canada, Europe, Russia and Alaska — accounting for 30 per cent of the world's land-based carbon stores — are burning at rates unprecedented in the past 10,000 years. Fires like those that raged this summer in the Northwest Territories (they burned through 3,381,000 hectares, an area some eight times greater than the 25-year average) release that carbon into another feedback loop: warmer temperatures prime forests for wildfires that release more carbon into the atmosphere and cause more warming. This in turn accelerates ice loss because ash from forest fires can also darken ice and melt it faster. The 2012 fires in Siberia released so much soot that a shocking 95 per cent of the surface of Greenland's icecap melted in only a few weeks. Not good when you consider that Greenland's icecap is fast coming apart in other ways: the Ilulissat glacier, mightiest of Greenland's many flowing rivers of ice, has lost an astounding 20 km in 20 years, the speed at which it's receding having virtually doubled in that time.

You might hear little about this (Canadian ice scientists are prohibited from holding fact-based press conferences on the crisis by the Federal government) but the reality is clear to those who study the earth. The extensive reduction in multiyear sea ice — defined as ice that has survived for two or more summers — is now reflected in the 10th edition of National Geographic's venerable world atlas, released in September this year. Based on trends observed over a 30-year period, multiyear ice is much smaller in area than on previous versions, the biggest visual change to the atlas after the breakup of the Soviet Union.

Though representing any dynamic environment in a fixed format is a challenge, maps open eyes to what's happening for those who can't view it up close. For his part, Vallely's up-close expedition "opened our eyes like we never imagined." In addition to experiencing the Arctic in a truly unique way, they were also privileged to speak with those who live there. They heard how winter now begins a full month later and features less-predictable weather patterns; how thinning sea ice poses new dangers to winter travel; of southern wildlife moving north, even polar bears and grizzly bears hybridizing.

"The Arctic is changing and it's changing dramatically," says Vallely. "We know that not because we rowed a boat through an area where it wouldn't have been possible in the recent past, but because the people whose lives are most affected told us so."

Leslie Anthony is a Whistler-based author, editor, biologist and bon vivant who has never met a mountain he didn't like.